I'm from Orange County area. Cypress/Garden Grove/Anaheim (Disney territory).
The races I almost got busted in were in Puente Hills/City of Industry area, so it's not too far from Ontario.
I heard Ontario races are even worse, cops totally being dick.
Anyway, races are cool, just don't get busted or your SOL.
My friends and I found a really good place at the border of two cities by my area and loud factories all around, so cops can't hear, and it's on border so cops don't go there too often. We raced there a couple times, just me and 2 other friends.....needless to say I beat them both! Teg's rule!